Olesian ore

From The Stargate Omnipedia

A volatile substance available in deposits on the planet Olesia. The prison island where the Stargate is located also has quantities of this ore. It was the Olesian Magistrate's hope that the "survivors" of the city of Atlantis would trade for some of the ore.

KEY EPISODE

Condemned - Colonel Sheppard's Puddle Jumper is shot from the sky by explosives charged with the Olesian ore.